This invention relates to the replacement of circuit components on electric circuit boards, such as replacement of an LED (light emitting diode) on a circuit board that is used in an instrument panel of an automotive vehicle.
An instrument panel of an automotive vehicle contains instrumentation and/or displays for presenting information about various operating conditions to the driver. One manner of displaying certain information is by the illumination of devices such as indicator lamps. Certain instrument panels comprise circuit boards on which indicator lamps are mounted. One type of electric device that is used as an indicator lamp is an LED (light emitting diode).
A cost-efficient way to fabricate an instrument panel circuit board involves the use of automated equipment that automatically assembles circuit components to a printed circuit board. The board has a front face on which bodies of the circuit components are disposed. The circuit components have terminals in the form of leads that extend from their bodies through pre-existing holes in the board. The process of automatically inserting the components into the board in that manner is sometimes referred to as stuffing a board.
The board has a rear face containing patterns of circuit traces that are laid out to establish desired electric circuits containing the circuit components. The circuit trace patterns are created by the selective removal of portions of a conductive layer on the rear face of the board during the process of fabricating the board prior to stuffing. After being stuffed, the board is processed by a wave-soldering machine that solders the respective terminals of the various components to the respective circuit traces.
An LED may be assembled directly to a circuit board in this way.
While LED""s generally have excellent reliability, one may occasionally fail. Where a failed LED has been directly assembled to a circuit board in the manner just described, its removal and replacement by a new LED may require considerably more effort than if the failed LED had been mounted in the first instance in a socket that would enable it to be simply extracted from the socket and replaced. Unsoldering and soldering a direct-mounted circuit component involve the use of concentrated heat at a sufficiently high temperature to melt solder. Care must be exercised in unsoldering a failed component, removing it from the board, assembling a new replacement component to the board, and finally soldering the replacement component in place. Lack of care has the potential to damage the replacement component, other board components, and/or the circuit board.
The use of sockets in the original manufacture of a board for enabling components inserted into them to be more easily replaced poses certain potential disadvantages. Because space on a circuit board is often limited, components are mounted in close proximity to one another, and consequently the use of sockets for allowing circuit components to be inserted and removed without unsoldering and re-soldering increases not only the size of a particular circuit board but also its initial cost. In light of the generally high reliability of LED""s, the inclusion of sockets for mounting them on a board to facilitate their replacement in event of failure is apt to impose a cost penalty on many circuit boards that would never experience a failed circuit component, and hence that does not seem to present a cost-efficient solution for facilitating replacement of the few that may fail.
One aspect of the present invention relates to a method for replacement of a direct-soldered circuit component that is believed to provide a better alternative both to unsoldering the failed component from the board and re-soldering a new one and to use of sockets in original board manufacture. The invention allows circuit boards to continue to be manufactured by cost-efficient methods involving direct soldering of components to the boards, yet allows a failed component to be replaced without unsoldering it from the board and then re-soldering a replacement component in its place.
While certain principles of the invention are specific to replacement of failed LED""s, principles may be applied to replacement of components other than LED""s. The invention is especially advantageous for replacement of components that are polarity-sensitive.
Being a two-terminal, polarity-sensitive component, an LED will illuminate only when sufficient voltage is applied with proper polarity across its terminals. While traces that feed an LED on a circuit board are designed to deliver the proper polarity when an LED is correctly connected, a replacement whose connections to the board traces are reversed will never illuminate when intended. The present invention offers the opportunity to avoid such an occurrence because it includes a polarizing feature.
One aspect of the present invention relates to a method for replacing an original board-mounted electric circuit component having plural terminals, each of which has conductive continuity with a respective conductive trace on the board, by a replacement component. A template feature is incorporated proximate the component and defines at least a portion of a zone from which board material is to be removed to enable the board to accept a replacement component having terminals corresponding to those of the original component. The board is modified by removing both the board-mounted component from the board and board material from the zone using the template feature. The replacement component is mounted on the board at the zone so as to establish conductive continuity of the respective traces on the board with respective terminals of the replacement component.
Another aspect of the present invention relates to a method for replacing an original board-mounted electric circuit component having plural terminals, each of which has conductive continuity with a respective conductive trace on the board, by a replacement component. A portion of the board that includes the board-mounted component is removed to create a through-hole in the board in place of the original component. The replacement component is mounted on the board by disposing, in the through-hole, a socket that has a receptacle for receiving the replacement component and providing conductive continuity of the respective traces on the board with respective terminals of the replacement component.
Still another aspect of the invention relates to a method for replacing an original board-mounted LED having a body disposed on a front face of the board and two terminals, each of which extends from the body through a respective through-hole in the board to attain conductive continuity with a respective conductive trace on a rear face of the board. The board is provided with plural through-openings that are separated by a bridge on which the original LED is disposed. The bridge, including the original LED, is removed from the board to create a socket-receiving through-hole in the board. A socket having a receptacle for receiving a replacement LED and providing conductive continuity of the respective traces on the board with respective terminals of the replacement LED is installed in the socket-receiving through-hole. A replacement LED is mounted in the socket.
Still another aspect of the invention relates to a method for replacing an original board-mounted LED in an instrument panel of an automotive vehicle. The LED comprises a body disposed on a front face of the board to face a driver of the vehicle and two terminals, each of which extends from the body through a respective through-hole in a bridge in the board on which the LED is disposed to attain conductive continuity with a respective conductive trace on a rear face of the board. The board also comprises plural through-openings that are separated by the bridge. First the board is accessed to enable the original LED to be replaced. The bridge, including the original LED, is removed from the board to create a socket-receiving through-hole in the board. A socket for mounting a replacement LED and providing conductive continuity of the respective traces on the board with respective terminals of a replacement LED is disposed in the socket-receiving through-hole, and the replacement LED is mounted in the socket.
Still another aspect of the invention relates to a circuit board comprising an original LED having a body disposed on a front face of the board and two terminals, each of which extends from the body through a respective through-hole in the board to attain conductive continuity with a respective conductive trace on a rear face of the board at a respective solder joint. The board has plural through-openings that are separated by a bridge on which the original LED is disposed. One segment of one trace extends along one approach of the bridge to one of the through-holes, and one segment of another trace extends along another approach of the bridge to the other through-hole. The one trace comprises another segment running along a margin of one of the through-openings, and the other trace comprises another segment running along a margin of another of the through-openings.
The foregoing, along with further aspects, features, and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. The disclosure includes drawings, briefly described as follows.